Display driver circuit and method for reducing influence of noise or dither

ABSTRACT

The present invention provides a display driver circuit. A determination circuit is configured to select a first mode for encoding first image data based on a first set of conditions respectively corresponding to a first set of modes. An encoder is configured to encode the first image data in the first mode. The determination circuit is additionally configured to select a second mode for encoding second image data received (n−1)th after the first image data are received; and to select a third mode for encoding third image data received (n)th after the first image data are received, based on a second set of conditions respectively corresponding to the first set of modes. A second condition in the second set of the conditions corresponding to the second mode includes a wider range of values than a first condition in the first set of the conditions corresponding to the second mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2018-0069241 filed on Jun. 15, 2018, in the KoreanIntellectual Property Office, the disclosures of which are incorporatedby reference herein in their entireties.

TECHNICAL FIELD

Example embodiments of the inventive concept relate to an electroniccircuit, and more particularly, to a display driver circuit and a methodto drive a display panel.

BACKGROUND

With regard to a display device, the demand on high-definition imagessuch as a high-definition (HD) image and an ultra-high definition (UHD)image is increasing. As the resolution of a display panel increases froma high-definition (HD) level to an ultra-high definition (UHD) level,the amount of image data including information of an image to bedisplayed on the display panel increases.

As the amount of the image data increases, the size of a memory storingthe image data is sharply increasing. Reduction of the size of thememory is desired to secure the competitiveness with regard to the sizeof a chip including the memory. Accordingly, in an image processingprocess of displaying an image on the display panel by using the imagedata, the image data may be encoded to decrease the amount of the imagedata.

Noise or dither occurring in the image processing process may cause anerror in which information included in the image data experiences anunintended change. The error arising from the image data may beamplified in the process of encoding the image data. The amplified errormay cause fine dithering and blinking of an image displayed on thedisplay panel. This phenomenon is referred to as a “flicker”. Theflicker may make user's eyes tired or concentration of the user low,making the user feel dizzy.

SUMMARY

Embodiments of the inventive concept provide a display driver circuitand a method for decreasing a flicker due to noise or dither.

According to some embodiments, a display driver circuit includes anencoding mode determination circuit and an encoder. The encoding modedetermination circuit is configured to select a first encoding mode forencoding first image data based on a first set of conditionsrespectively corresponding to a first set of encoding modes. The encoderis configured to encode the first image data in the first encoding mode.The encoding mode determination circuit is additionally configured toselect a second encoding mode for encoding second image data received(n−1)th after the first image data are received; and to select a thirdencoding mode for encoding third image data received (n)th after thefirst image data are received, based on a second set of conditionsrespectively corresponding to the first set of encoding modes. A secondcondition in the second set of the conditions corresponding to thesecond encoding mode includes a wider range of values than a firstcondition in the first set of the conditions corresponding to the secondencoding mode.

According to some embodiments, which may include the aforementionedembodiments, a display driver circuit includes an encoding modedetermination circuit and an encoder. The encoding mode determinationcircuit is configured to receive first image data, second image data,and third image data sequentially and successively; select a firstencoding mode for encoding the first image data among a plurality ofencoding modes select a second encoding mode for encoding the secondimage data among the encoding modes based on a first set of conditionsrespectively corresponding to the encoding modes, the first set ofconditions including a first condition corresponding to the secondencoding mode; and select a third encoding mode for encoding the thirdimage data among the encoding modes based on a second set of conditionsrespectively corresponding to the encoding modes. The second set ofconditions includes a second condition corresponding to the thirdencoding mode. The encoder is configured to encode the first image datain the first encoding mode that selected, and to encode the second imagedata in the second encoding mode that selected. The second encoding modeis different from the first encoding mode, a second range correspondingto the second condition is wider range than a first range correspondingto the first condition.

A display driver circuit includes an encoding mode determination circuitand an encoder. The encoding mode determination circuit is configured todetermine a first encoding mode for encoding first image data based on afirst set of conditions corresponding to encoding modes, the first setof conditions including a first condition, and determine a secondencoding mode for encoding second image data received immediatelyfollowing the first image data, based on a second set of conditionscorresponding to the encoding modes, the second set of conditionsincluding a second condition. The encoder is configured to encode thefirst image data in the first encoding mode. The first condition in thefirst set includes a first range or set of criteria, and the secondcondition in the second set includes a second range or second set ofcriteria, wherein the second range is wider than and includes the firstrange, or the second set of criteria includes the first set of criteria.

BRIEF DESCRIPTION OF THE FIGURES

The above and other objects and features of the inventive concept willbecome apparent by describing in detail exemplary embodiments thereofwith reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating an exemplary configuration of anelectronic device including a display driver circuit according toembodiments of the inventive concept.

FIG. 2 is a block diagram illustrating an exemplary configurationassociated with a display driver circuit of FIG. 1.

FIG. 3 is a block diagram illustrating an exemplary configuration of adisplay driver circuit of FIG. 2.

FIG. 4 is a block diagram illustrating an exemplary configuration of anencoding mode determination circuit of FIG. 3.

FIG. 5 is a timing diagram for describing an exemplary operation of adisplay driver circuit of FIG. 3.

FIG. 6 is a timing diagram for describing an exemplary operation of adetermination circuit of FIG. 4.

FIG. 7 is a timing diagram for describing an exemplary operation of adetermination circuit of FIG. 4.

FIG. 8 is a timing diagram for describing an exemplary operation of adetermination circuit of FIG. 4.

FIG. 9 is a conceptual diagram for describing a difference between afirst set of conditions and a second set of conditions of FIG. 8.

FIG. 10 is a table indicating an embodiment of a first set of conditionsand a second set of conditions of FIG. 8.

FIG. 11 is a table indicating an embodiment of a conversion valueobtained from image data.

FIG. 12 is a flowchart for describing an exemplary operation of adisplay driver circuit from a time when first image data of FIG. 5 arereceived to a time when an encoding mode of second data is determined.

FIG. 13 is a flowchart for describing an operation of an encoding modedetermination circuit until an encoding mode of second image data isdetermined after first image data of FIG. 5 are received.

FIG. 14 is a flowchart for describing an operation of an adjustingcircuit until an encoding mode of third data is determined after secondimage data of FIG. 5 are received.

DETAILED DESCRIPTION

FIG. 1 is a block diagram illustrating an exemplary configuration of anelectronic device including a display driver circuit according toembodiments of the inventive concept. For example, an electronic device1000 may be implemented with one of various types of electronic devicessuch as a television, a smartphone, a tablet personal computer (PC), alaptop PC, an e-book reader, an MP3 player, a wearable device, etc.

The electronic device 1000 may include various electronic circuits. Forexample, the electronic circuits of the electronic device 1000 mayinclude a display driver circuit 100, a display panel 1800, an imageprocessing block 1100, a communication block 1200, an audio processingblock 1300, a buffer memory 1400, a nonvolatile memory 1500, a userinterface 1600, and a main processor 1700.

The display driver circuit 100 may receive image data from the mainprocessor 1700. The display driver circuit 100 may display an image onthe display panel 1800 based on the received image data. Exemplaryconfigurations and exemplary operations of the main processor 1700, thedisplay driver circuit 100, and the display panel 1800 will be describedwith reference to FIG. 2.

As is traditional in the field of the inventive concepts, embodimentsare described, and illustrated in the drawings, in terms of functionalblocks. Those skilled in the art will appreciate that these blocks arephysically implemented by electronic (or optical) circuits such as logiccircuits, discrete components, microprocessors, hard-wired circuits,memory elements, wiring connections, and the like, which may be formedusing semiconductor-based fabrication techniques or other manufacturingtechnologies. In the case of the blocks being implemented bymicroprocessors or similar, they may be programmed using software (e.g.,microcode) to perform various functions discussed herein and mayoptionally be driven by firmware and/or software. Alternatively, eachblock may be implemented by dedicated hardware, or as a combination ofdedicated hardware to perform some functions and a processor (e.g., oneor more programmed microprocessors and associated circuitry) to performother functions. Also, each block of the embodiments may be physicallyseparated into two or more interacting and discrete blocks withoutdeparting from the scope of the inventive concepts. Further, the blocksof the embodiments may be physically combined into more complex blockswithout departing from the scope of the inventive concepts.

The image processing block 1100 may receive light through a lens 1110.An image sensor 1120 and an image signal processor 1130 included in theimage processing block 1100 may generate image data associated with anexternal subject, based on the received light.

The communication block 1200 may exchange signals with an externaldevice/system, external to the electronic device 1000, through anantenna 1210. A transceiver 1220 and a MODEM (Modulator/Demodulator)1230 of the communication block 1200 may process signals, which areexchanged with the external device/system, in compliance with variouswireless communication protocols.

The audio processing block 1300 may process sound information by usingan audio signal processor 1310, thus playing and outputting the audio.The audio processing block 1300 may receive an audio input through amicrophone 1320. The audio processing block 1300 may output the playedaudio through a speaker 1330.

The buffer memory 1400 may store data which are used for an operation ofthe electronic device 1000. For example, the buffer memory 1400 maytemporarily store data processed or to be processed by the mainprocessor 1700. For example, the buffer memory 1400 may include avolatile memory such as a static random access memory (SRAM), a dynamicRAM (DRAM), or a synchronous DRAM (SDRAM), and/or a nonvolatile memorysuch as a phase-change RAM (PRAM), a magneto-resistive RAM (MRAM), aresistive RAM (ReRAM), or a ferroelectric RAM (FRAM).

The nonvolatile memory 1500 may store data regardless of power supply.For example, the nonvolatile memory 1500 may include at least one ofvarious nonvolatile memories such as a flash memory, a PRAM, an MRAM, aReRAM, and a FRAM. For example, the nonvolatile memory 1500 may includea removable memory such as a secure digital (SD) card, and/or anembedded memory such as an embedded multimedia card (eMMC).

The user interface 1600 may arbitrate communication between a user andthe electronic device 1000. For example, the user interface 1600 mayinclude input interfaces such as a keypad, a button, a touch screen, atouch pad, a gyroscope sensor, a vibration sensor, and an accelerationsensor. For example, the user interface 1600 may include outputinterfaces such as a motor and a light emitting diode (LED) lamp.

The main processor 1700 may control overall operations of the componentsof the electronic device 1000. The main processor 1700 may processvarious operations for the purpose of operating the electronic device1000. For example, the main processor 1700 may be implemented with anoperation processing device/circuit, which includes one or moreprocessor cores, such as a general-purpose processor, a special-purposeprocessor, an application processor, or a microprocessor.

For example, the main processor 1700 may send image data to the displaydriver circuit 100. The display driver circuit 100 may drive the displaypanel 1800 based on the image data, for the purpose of displaying animage on the display panel 1800. An image to be displayed on the displaypanel 1800 may vary with an encoding mode in which image data areencoded at the display driver circuit 100.

For example, the image data may be stored in advance to the nonvolatilememory 1500, and the main processor 1700 may send the image data storedin the nonvolatile memory 1500 to the display driver circuit 100. Asanother example, the image data may be received in real time through thecommunication block 1200, the received image data may be stored to thebuffer memory 1400, and the main processor 1700 may send the image datastored in the buffer memory 1400 to the display driver circuit 100.

However, the exemplary components illustrated in FIG. 1 are provided forbetter understanding, and are not intended to limit the inventiveconcept. The electronic device 1000 may not include one or more of thecomponents illustrated in FIG. 1 or may further include at least onecomponent not illustrated in FIG. 1.

FIG. 2 is a block diagram illustrating an exemplary configurationassociated with a display driver circuit of FIG. 1.

The main processor 1700 may send image data to the display drivercircuit 100. For example, the main processor 1700 may communicate withthe display driver circuit 100 in compliance with an interface protocol(e.g., a display serial interface (DSI) protocol of the mobile industryprocessor interface (MIPI) alliance) supported by the electronic device1000.

The display driver circuit 100 may display an image on the display panel1800 based on image data received from the main processor 1700. As thesize of the image data becomes larger, power consumption may increaseupon processing the image data for the purpose of displaying an image onthe display panel 1800. Also, as the size of the image data becomeslarger, the size of a memory storing the image data may increase.Accordingly, the display driver circuit 100 may encode and use thereceived image data.

The display driver circuit 100 may determine an encoding mode forencoding the received image data. The display driver circuit 100 mayencode the received image data using the determined encoding mode.

The display panel 1800 may display an image which is based on the imagedata received from the display driver circuit 100. For example, thedisplay panel 1800 may be implemented with various forms of panels, suchas a crystal display (LCD) panel, a light-emitting diode (LED) displaypanel, an organic LED (OLED) display panel, and an active matrix OLED(AMOLED) display panel.

The display panel 1800 may include a pixel array which includes aplurality of pixels. The pixel array may correspond to a region which isused as a screen where an image is displayed. Each of the pixels of thepixel array may be independently driven by the display driver circuit100. The display driver circuit 100 may drive the display panel 1800based on a driving signal.

An image to be displayed on the display panel 1800 may be composed ofone or more block images each including one or more pixels. The imagedata received from the display driver circuit 100 may includeinformation about one or more block images.

A color which is expressed in an image or one or more block images mayvary with an encoding mode which is determined by the display drivercircuit 100. A color which is expressed in an image or one or more blockimages may be determined depending on a color space applied to imagedata. Color spaces may include GRAY (Gray model), RGB (Red Green Bluecolor model), RGBW (Red Green Blue White color model), and YUV (YUVcolor image pipeline). The color spaces may correspond to encodingmodes, respectively. For example, in the case where the determinedencoding mode corresponds to the GRAY color space, a color to beexpressed in an image may be a combination of black and white. Foranother example, in the case where the determined encoding modecorresponds to the RGB color space, a color to be expressed in an imagemay be a combination of red (R), green (G), and blue (B).

The display driver circuit 100 may receive image data sequentially fromthe main processor 1700. The display panel 1800 may display an imagebased on the received image data in order in which the image data arereceived. For example, the display driver circuit 100 may receive firstimage data from the main processor 1700 and may then receive secondimage data from the main processor 1700. The display panel 1800 maydisplay a first image based on the first image data and may then displaya second image based on the second image data.

In the following descriptions, the first image data and the second imagedata are any two data of a plurality of image data received sequentiallyand successively. The first image data and the second image data arereceived sequentially and successively. The first image data are imagedata first received among the two image data. The second image data areimage data received immediately following the first image data. Note,however, that unless the context indicates otherwise, terms such as“first,” “second,” etc., may be used in the specification or claimssimply to name certain objects or steps, as a naming convention, andtherefore do not necessarily connote an order or location of the itemsthey describe.

An encoding mode of the first image data and an encoding mode of thesecond image data may be determined differently at the display drivercircuit 100. For example, the encoding mode of the first image data maybe a first encoding mode, and the encoding mode of the second image datamay be a second encoding mode different from the first encoding mode.However, in certain instances, a first encoding mode and a secondencoding mode may refer to the same mode applied at different times.Thus, two encoding modes that use different encoding schemes will bedescribed as different encoding modes, and two encoding modes that usethe same encoding scheme will be described as the same encoding mode.

In the case where the encoding mode of the first image data and theencoding mode of the second image data are different, a color to beexpressed in the first image and a color to be expressed in the secondimage may be different. In the case where colors expressed in two imagesdisplayed sequentially and successively are different from each other, aflicker may occur. The flicker is a phenomenon in which an imagedisplayed on the display panel 1800 blinks or dithers finely. Theflicker may make user's eyes tired or concentration of the user low,thus making the user feel dizzy.

A plurality of image data which are sent sequentially and successivelyfrom the main processor 1700 may include the same or similarinformation. For example, according to exemplary embodiments, theplurality of image data which are sent sequentially and successivelyfrom the main processor 1700 may include the same or similar pixelvalues. In this case, encoding modes for the plurality of image data maybe determined to be identical to each other. For example, in the casewhere the plurality of image data include the same information, thedisplay panel 1800 may display a still image.

However, even though the plurality of image data including the sameinformation are sent from the main processor 1700, noise or dither maycause an error in which information included in image data experiencesan unintended change. The noise or dither may occur in an imageprocessing process. Also, the noise or dither may occur in the processwhere image data are received from the display driver circuit 100 fromthe main processor 1700.

The error arising from the image data may be amplified in the process ofencoding the image data. For example, in the case where the informationincluded in the second image data has an unintended change, even thoughthe second image data include the same information as the first imagedata, encoding modes may be determined differently with regard to thefirst and second image data. In the case where colors which arerespectively expressed in two images to be displayed in a row based ontwo received image data in a row are different from each other, theflicker may occur.

The display driver circuit 100 according to an embodiment of theinventive concept may determine an encoding mode of each of a pluralityof image data based on variable conditions. Accordingly, encoding modesof a plurality of image data received in a row may be prevented frombeing determined differently due to the noise or dither. As a result,the flicker due to the noise or dither may decrease. Configurations andoperations of the display driver circuit 100 will be described withreference to FIGS. 3 to 14.

FIG. 3 is a block diagram illustrating an exemplary configuration of adisplay driver circuit of FIG. 2.

The display driver circuit 100 may include an interface 110, an encodingmode determination circuit 120, an encoder 130, a memory 140, a decoder150, an image processing circuit 160, and a source driver 170. However,FIG. 3 shows only an exemplary configuration of the display drivercircuit 100, and the display driver circuit 100 may further includecomponents not illustrated in FIG. 3. Alternatively, the display drivercircuit 100 may not include one or more of the components illustrated inFIG. 3.

The interface 110 may receive image data from the main processor 1700.The received image data may include information about an image to bedisplayed on the display panel 1800. The interface 110 may send thereceived image data to other components in the display driver circuit100.

The encoding mode determination circuit 120 may receive image data fromthe interface 110. The encoding mode determination circuit 120 maydetermine an encoding mode for encoding the received image data. As anexample, a color which is expressed in an image to be displayed on thedisplay panel 1800 may vary with the determined encoding mode.

The encoding mode determination circuit 120 may generate a signal s1.The signal s1 may include information about the determined encodingmode.

The encoder 130 may receive image data from the interface 110. Theencoder 130 may receive the signal s1 from the encoding modedetermination circuit 120. The encoder 130 may encode image data in theencoding mode which is determined by the encoding mode determinationcircuit 120, based on the signal s1.

The memory 140 may receive the image data encoded by the encoder 130.The memory 140 stores the encoded image data. The memory 140 may includea volatile memory and/or a nonvolatile memory. For example, the memory140 may include at least one of a volatile memory (a DRAM, an SRAM, oran SDRAM) and a nonvolatile memory (a PROM, an EPROM, a flash ROM, or aflash memory).

The decoder 150 receives image data stored in the memory 140. Thedecoder 150 may decode the image data received from the memory 140. Inthe case where the display driver circuit 100 includes an encoder forthe purpose of encoding image data, the display driver circuit 100 mayinclude the decoder 150 corresponding to an encoding format of theencoder 130.

The image processing circuit 160 receives the image data decoded by thedecoder 150. The image processing circuit 160 may process the decodedimage data, thus improving the quality of the image data.

The source driver 170 receives the image data processed by the imageprocessing circuit 160. The source driver 170 outputs a driving signalbased on the processed image data. The source driver 170 drives datalines connected to the pixels of the display panel 1800. The sourcedriver 170 may drive the data lines based on the driving signal suchthat an image is displayed on the display panel 1800. Therefore, thesource driver 170 may drive the display panel 1800.

The interface 110 may receive image data sequentially from the mainprocessor 1700. The interface 110 may send the received image data toother components in the display driver circuit 100 in order in whichimage data are received. For example, in the case where the first imagedata and the second image data are received sequentially andsuccessively from the main processor 1700, the interface 110 may sendthe first image data to the encoding mode determination circuit 120 andthe encoder 130 and may then subsequently send the second image data tothe encoding mode determination circuit 120 and the encoder 130.

The encoding mode determination circuit 120 may receive image datasequentially from the interface 110. The encoding mode determinationcircuit 120 may determine an encoding mode of image data in order inwhich image data are received. For example, in the case where the firstimage data and the second image data are received sequentially andsuccessively from the interface 110, the encoding mode determinationcircuit 120 may first determine an encoding mode of the first image dataand may then determine an encoding mode of the second image data.

The encoder 130 may encode the first image data in the determinedencoding mode of the first image data. The memory 140 may store theimage data encoded by the encoder 130. The decoder 150 may decode thefirst image data stored in the memory 140. The encoding modedetermination circuit 120 may receive the first image data stored in thememory 140 or the first image data decoded in the decoder 150. Theencoding mode determination circuit 120 may identify the encoding modeof the first image data based on the first image data thus received. Theencoding mode determination circuit 120 may determine the encoding modeof the second image data based on the identified encoding mode of thefirst image data.

FIG. 4 is a block diagram illustrating an exemplary configuration of anencoding mode determination circuit of FIG. 3.

An operation in which the encoding mode determination circuit 120determines an encoding mode of the second image data based on anencoding mode of the first image data will be described with referenceto FIG. 4. As described with reference to FIG. 3, the encoding modedetermination circuit 120 may receive the first image data stored in thememory 140 or decoded first image data. An operation in which the firstimage data are decoded by the decoder 150 after being sent from theinterface 110 is described with reference to FIG. 3, and thus,additional description will be omitted to avoid redundancy.

The encoding mode determination circuit 120 may include a generatingcircuit 121, an adjusting circuit 122, and a determination circuit 123.

The generating circuit 121 may receive the second image data from theinterface 110. The generating circuit 121 may generate a conversionvalue which is based on the second image data. The conversion value maybe generated based on pixel values included in the second image data,but the disclosure is not limited thereto. The second image data mayinclude pixel values associated with a color which is expressed in animage to be displayed on the display panel 1800. For example, the secondimage data may include a red (R) pixel value, a green (G) pixel value,and a blue (B) pixel value. However, the inventive concept is notlimited thereto, and the second image data may include pixel values ofvarious components. For example, the second image data may include a red(R) pixel value, a green (G) pixel value, a blue (B) pixel value, and awhite (W) pixel value. For another example, the second image data mayinclude a pixel value of a Y channel, a pixel value of a U channel, anda pixel value of a V channel.

The conversion value may be generated based on difference values betweenthe pixel values included in the second image data. A pixel value mayrepresent a brightness, or intensity of a pixel, for example. Theconversion value may be the maximum value among the difference valuesbetween the pixel values included in the second image data. For example,in the case where the R pixel value, the G pixel value, and the B pixelvalue included in the second image data are “10”, “15”, and “30”,respectively, the conversion value may be “20” (=30−10). However, theinventive concept is not limited thereto, and the conversion value maybe generated based on pixel values included in the second image data, invarious methods. For example, the conversion value may be generatedbased on the remaining pixel values of the pixel values of the secondimage data other than the least significant bit (LSB). For anotherexample, the conversion value may be an average value of the pixelvalues of the second image data. The generating circuit 121 may generatea signal s2. The signal s2 may include information about the conversionvalue.

The adjusting circuit 122 may receive the first image data stored in thememory 140 or decoded first image data. The adjusting circuit 122 mayidentify an encoding mode of the first image data based on the receivedfirst image data. For example, a header of the received first image datamay include information about the encoding mode of the first image data.The adjusting circuit 122 may identify an encoding mode in which thefirst image data are encoded, based on information included in theheader of the received first image data.

The adjusting circuit 122 may include information about a first set ofconditions. The conditions in the first set may correspond to encodingmodes, respectively. The conditions in the first set may be updatedperiodically or randomly. In the case where the second image data arereceived periodically or after the display driver circuit 100 is reset,the first set of conditions may be used to determine the encoding modeof the second image data. The first set of conditions may be a defaultset that includes a plurality of conditions, each conditioncorresponding to an encoding mode.

The adjusting circuit 122 may include information about a second set ofconditions. The conditions in the second set may correspond to theencoding modes, respectively. Compared to the first set of conditions,the second set may be an adjusted set of conditions, including aplurality of adjusted conditions, different from correspondingconditions of the first set of conditions, each adjusted conditioncorresponding to an encoding mode.

The adjusting circuit 122 may generate the conditions in the second set,and thus may use an adjusted set of conditions compared to the firstset, based on the encoding mode of the first image data and the firstset of conditions. For example, a first condition in the second setcorresponding to the encoding mode of the first image data may bedifferent from a first condition in the first set corresponding to theencoding mode of the first image data. The different conditions mayoverlap in some respects, however. For example, if the first conditionin the first set includes a first range of values that correspond to aparticular encoding mode, the first condition in the second set mayinclude a wider range of values that includes the first range of valuesto correspond to the same particular encoding mode. As another example,a first range for a first condition in the second set corresponding to aparticular encoding mode of the first image data may have a lower valueand a higher upper value than a first range of the first condition inthe first set corresponding to the particular encoding mode of the firstimage data. The first set of conditions and the second set of conditionswill be described further with reference to FIGS. 6 to 8. The adjustingcircuit 122 may be referred to herein as a condition set selectioncircuit, or condition set setting circuit, since it may select ordetermine the condition set to be used (e.g., which may be as a resultof adjusting the previous condition set).

The adjusting circuit 122 may generate a signal s3. The signal s3 mayinclude information about the first set of conditions or informationabout the second set of conditions. For example, periodically or in thecase where the display driver circuit 100 is reset, the signal s3 mayinclude information designating a first (e.g., default) set ofconditions.

The determination circuit 123, also described as a mode selectioncircuit, may receive the signals s2 and s3. The signal s2 may includeinformation about the conversion value obtained from the second imagedata (e.g., it may include the determined conversion value). The signals3 may include information about the first set of conditions or thesecond set of conditions (e.g., it may include the first set ofconditions or the second set of conditions).

The determination circuit 123 may determine, or select, the encodingmode of the second image data based on the conversion value andinformation about the conditions included in the signal s3. For example,in the case where the conversion value for the second image datasatisfies a first condition corresponding to the first encoding mode(which could be based on either the first set of conditions or thesecond set of conditions), the encoding mode of the second image datamay be determined as a first encoding mode of the encoding modes.

The determination circuit 123 may generate the signal s1 includinginformation about the encoding mode of the second image data (e.g., anindicator indicating which encoding mode to use for the second imagedata).

The encoder 130 may receive the signal s1. The encoder 130 may receivethe second image data from the interface 110. The encoder 130 may encodeimage data in the encoding mode which is determined by the determinationcircuit 123, based on the signal s1.

FIG. 5 is a timing diagram for describing an operation of a displaydriver circuit of FIG. 3. For better understanding, FIGS. 3 and 5 willbe referenced together.

However, the inventive concept is not limited to an operation of adisplay driver circuit which will be described with reference to FIG. 5,and the display driver circuit according to an embodiment of theinventive concept may operate during a time interval.

An operation in which the display driver circuit 100 determines theencoding mode of first image data in the case where the display drivercircuit 100 is reset after previous image data are received and beforethe first image data are received will be described with reference toFIG. 5. Also, an operation in which the display driver circuit 100determines an encoding mode of second image data based on the firstimage data decoded by the decoder 150 will be described with referenceto FIG. 5. However, the inventive concept is not limited thereto, andthe display driver circuit 100 may determine the encoding mode of thesecond image data based on the first image data stored in the memory140.

At a time point t1, the interface 110 receives the image data (describedhere as “previous image data”) from the main processor 1700.

At a time point t2, the encoding mode determination circuit 120 receivesthe previous image data from the interface 110. The display drivercircuit 100 may be reset before the encoding mode determination circuit120 determines the encoding mode of the previous image data. In the casewhere the display driver circuit 100 is reset, the display drivercircuit 100 may stop an operation associated with the received previousimage data. In this case, the encoding mode determination circuit 120may not determine the encoding mode of the previous image data.

At a time point t3, the interface 110 receives the second image datafrom the main processor 1700.

At the time point t4, the encoding mode determination circuit 120receives first image data from the interface 110. The first image datamay be image data first received after the display driver circuit 100 isreset. The encoding mode determination circuit 120 determines theencoding mode of the first image data. The encoding mode determinationcircuit 120 may use a first set of conditions (e.g., a default set ofconditions) for the purpose of determining the encoding mode of thefirst image data. When a conversion value obtained from the first imagedata satisfies a first condition in the first set of conditions, theencoding mode determination circuit 120 determines, or selects, theencoding mode of the first image data as a first encoding modecorresponding to the first condition in the first set of conditions.However, the inventive concept is not limited thereto, and the first setof conditions (e.g., a default set of conditions) may be usedperiodically, and not only after a reset, to determine the encoding modeof image data received from the main processor 1700.

At a time point t5, the encoder 130 encodes the first image data in thedetermined encoding mode.

At a time point t6, the memory 140 stores the encoded first image data.

At the time point t7, the decoder 150 decodes the first image datastored in the memory 140. Also, at the time point t7, the interface 110receives second image data from the main processor 1700. In thefollowing descriptions, the second image data are data receivedimmediately following the first image data, and may be described withrespect to the first image data, as the next image data, or consecutiveimage data.

At a time point t8, the display panel 1800 displays an image based onthe first image data.

Also, at the time point t8, the encoding mode determination circuit 120receives the second image data from the interface 110. The encoding modedetermination circuit 120 may also receive the decoded first image dataat the time point t8. The encoding mode determination circuit 120 mayidentify the encoding mode of the first image data based on the decodedfirst image data. In one embodiment, the encoding mode determinationcircuit 120 may select or generate the second set of conditions based onthe encoding mode of the first image data. For example, the second setof conditions may be selected or generated based on the encoding mode ofthe first image data and the first set of conditions. The conditions inthe second set may be conditions obtained by adjusting the first set ofconditions.

For example, in the case where the encoding mode of the first image datais determined as the first encoding mode based on the first condition inthe first set of conditions corresponding to a first range or set ofcriteria, the first condition in the second set of conditionscorresponding to the first encoding mode may include the entire firstrange or set of criteria, and additional range values or criteria thatexpand the first range or set of criteria included in the firstcondition in the first set corresponding to the first encoding mode. Foranother example, a range for first condition in the second set may havehigher lower and upper end values than a range which the first conditionin the first set has.

However, the inventive concept is not limited thereto, and the firstimage data and the second image data may not be received sequentiallyand successively. In this case, the second set of conditions may begenerated based on the first set of conditions and an encoding mode ofimage data immediately before the second image data are received.

The encoding mode determination circuit 120 may use the second set ofconditions for the purpose of determining the encoding mode of thesecond image data. As an example, in the case where a conversion valueobtained from the second image data satisfies the first condition in thesecond set, the encoding mode determination circuit 120 determines theencoding mode of the second image data as the first encoding modecorresponding to the first condition in the second set.

Between a time point t9 and a time point t12, the display driver circuit100 may provide operations corresponding to the operations from the timepoint t5 to the time point t8. Thus, additional description will beomitted to avoid redundancy.

At a time point t11, the interface 110 may receive third image data fromthe main processor 1700. In the following descriptions, the third imagedata are data which are received immediately following the second imagedata.

At the time point t12, the encoding mode determination circuit 120receives the third image data from the interface 110. Also, at the timepoint t12, the encoding mode determination circuit 120 receives thedecoded second image data. The encoding mode determination circuit 120may identify the encoding mode of the second image data based on thedecoded second image data.

In some situations, the encoding mode determination circuit 120 mayadjust the second set of conditions based on the encoding mode of thesecond image data.

In the case where the encoding mode of the second image data isidentical to the encoding mode of the first image data, the encodingmode determination circuit 120 may maintain the second set ofconditions. In this case, the encoding mode determination circuit 120may determine the encoding mode of the third image data based on thesecond set of conditions.

In the case where the encoding mode of the second image data isdifferent from the encoding mode of the first image data, the encodingmode determination circuit 120 may adjust the second set of conditions,and thus, the second set of conditions may be changed and a differentset of conditions (e.g., a third set, which may be different from thefirst and second sets, or the same as the first set) may be selected andused. For example, the third set of conditions in this case could revertback to the first, default set. As in the case where the second set ofconditions are selected or generated, and thus used, based on theencoding mode of the first image data, the second set of conditions inthe above situation may be adjusted based on the encoding mode of thesecond image data to form a third set of conditions. Also, as in thecase where the second set of conditions are selected or generated, andthus used, based on the encoding mode of the first image data, a thirdset of conditions in the above situation may be selected or generated,and thus used, based on the encoding mode of the second image data. Theencoding mode determination circuit 120 may determine the encoding modeof the third image data based on the third set of conditions thusadjusted and/or selected. An operation in which the second set ofconditions is adjusted will be described with reference to FIGS. 6 and7.

The present invention is not limited to this, the second image data maybe (n−1)th received data after the first image data is received. Also,the third image data may be (n)th received data after the first imagedata is received. The n is integer greater than 2. The case where n is 2has been described with reference to FIG. 5. In this case, the encodingmode of the second image data is not compared with the encoding mode ofthe first image data, and is compared with the encoding mode of theimage data received (n−2) after the first image data is received.

Also, in the case where the third image data are image data firstreceived after the display driver circuit 100 is reset, the encodingmode determination circuit 120 may use the first set of conditions(e.g., a default set of conditions) for the purpose of determining theencoding mode of the third image data.

Also, at the time point t12, the display panel 1800 may display an imagebased on the second image data. The image based on the second image datamay be displayed after an image based on the first image data isdisplayed on the display panel 1800.

FIG. 6 is a timing diagram for describing a determination circuit ofFIG. 4. For better understanding, FIGS. 4 and 5 will be referencedtogether with FIG. 6.

An operation in which the encoding mode determination circuit 120determines encoding modes of the first image data, the second imagedata, and the third image data in the case where an encoding mode of thefirst image data and an encoding mode of the second image data aredifferent will be described with reference to FIG. 6.

At the time point t4, the encoding mode determination circuit 120determines the encoding mode of the first image data. The generatingcircuit 121 may generate a conversion value cv0 which is based on thefirst image data. The adjusting circuit 122 may include informationabout a first set of conditions c01, c02, c03, c04, and c05 (hereinaftercollectively referred to as “c0”). For example, the first set ofconditions c0 may correspond to encoding modes m1, m2, m3, m4, and m5(hereinafter collectively referred to as “m0”). The first set ofconditions may be a default set of conditions, and may be stored in theadjusting circuit 122.

The determination circuit 123 determines the encoding mode of the firstimage data based on the information about the conversion value cv0 andthe first set of conditions c0. For example, in the case where theconversion value cv0 satisfies the condition c02 in the first set ofconditions corresponding to the encoding mode m2, the determinationcircuit 123 determines the encoding mode of the first image data as theencoding mode m2.

At the time point t8, the encoding mode determination circuit 120determines the encoding mode of the second image data. The generatingcircuit 121 may generate a conversion value cv1 which is based on thesecond image data. The adjusting circuit 122 receives the first imagedata stored in the memory 140 or decoded first image data. The adjustingcircuit 122 identifies the encoding mode m2 of the first image databased on the received first image data.

The adjusting circuit 122 may select or generate a second set ofconditions c11, c12, c13, c14, and c15 (hereinafter collectivelyreferred to as “c1”) based on the encoding mode m2 of the first imagedata and the first set of conditions c0. The second set of conditions c1may correspond to the encoding modes m0, respectively. For example, thesecond set of conditions may be pre-stored in the adjusting circuit 122,or may be generated based on a pre-stored adjustment scheme, dependingon the conversion value cv1. For example, if the conversion value cv1 iswithin a particular distance from the range that corresponds to theencoding mode m2 of the first image data (e.g., the range associatedwith the condition c02), then a particular second set of conditions maybe selected or generated.

The condition c12 corresponding to the encoding mode m2 of the secondimage data may be generated to be related to the condition c02corresponding to the encoding mode m2 of the second image data. Forexample, a range included in the condition c12 may also be included thecondition c02. For another example, part of a range included in thecondition c12 may be above a range included in the condition c02.

The remaining conditions c11, c13, c14, and c15 may be generated basedon a relationship between the conditions c02 and c12 and the conditionsc01, c03, c04, and c05. For example, the remaining conditions c11, c13,c14, and c15 may be obtained by adjusting the conditions c02, c03, c04,and c05 such that the condition c12 and the conditions c01, c03, c04,and c05 do not overlap each other.

As one example, the condition c12 may be determined based on an errorvalue and the condition c02. The error value may be a valuecorresponding to noise or dither which occurs in the image processingprocess. The error value may be updated periodically or randomly. Theerror value may be updated based on a change of the noise or dither. Theremaining conditions c11, c13, c14, and c15 may be generated based onthe error value and the conditions c01, c03, c04, and c05. Arelationship between the first set of conditions c0, the second set ofconditions c1, and the error value will be described with reference toFIGS. 8 and 9.

The determination circuit 123 may determine the encoding mode of thesecond image data based on the information about the conversion valuecv1 and the second set of conditions c1. For example, in the case wherethe conversion value cv1 satisfies the condition c11 corresponding tothe encoding mode m1, the determination circuit 123 determines theencoding mode of the second image data as the encoding mode m1.

At the time point t12, the encoding mode determination circuit 120determines the encoding mode of the third image data. The generatingcircuit 121 may generate a conversion value cv2 which is based on thethird image data. The adjusting circuit 122 may adjust the conditions c1in the second set based on the encoding mode m1 of the second imagedata.

The adjusting circuit 122 may identify the encoding mode m1 of thesecond image data. The adjusting circuit 122 may adjust the conditionsc1 in the second set based on the encoding mode m1 of the second imagedata and the first set of conditions c0. The adjusting circuit 122 mayadjust the conditions c1 in the second set in a method which is similarto a method of generating the second set of conditions c1 at the timepoint t8.

The second set of conditions c1 may be changed to a third set ofconditions c21, c22, c23, c24, and c25 (hereinafter collectivelyreferred to as “c2”). The conditions c2 in the third set adjusted maycorrespond to the encoding modes m0, respectively.

The condition c21 corresponding to the encoding mode m1 of the thirdimage data may be generated based on the condition c01 corresponding tothe encoding mode m1 of the first image data. For example, a range forthe condition c21 may include a range for the condition c01. For anotherexample, a range for the condition c21 may be at least in part above arange of the condition c01. The remaining conditions c22, c23, c24, andc25 may be generated based on a relationship between the conditions c01and c21 and the conditions c02, c03, c04, and c05.

FIG. 7 is a timing diagram for describing an exemplary operation of adetermination circuit of FIG. 4. For better understanding, FIGS. 4 and 5will be referenced together with FIG. 7.

An operation in which the encoding mode determination circuit 120determines an encoding mode of the third image data in the case where anencoding mode of the second image data is identical to an encoding modeof the first image data will be described with reference to FIG. 7.

The encoding mode determination circuit 120 may provide operations whichcorrespond to or are identical to the operations described withreference to FIG. 4. Thus, additional description will be omitted toavoid redundancy.

The determination circuit 123 may determine the encoding mode of thesecond image data as the encoding mode m2 identical to the encoding modeof the first image data.

In the case where the encoding mode of the second image data isidentical to the encoding mode of the first image data, the encodingmode determination circuit 120 may maintain the second set of conditionsc1. Accordingly, the encoding mode determination circuit 120 maydetermine the encoding mode of the third image data based on the secondset of conditions c1 instead of the second set of adjusted conditions c2(e.g., a third set of conditions) illustrated in FIG. 6.

FIG. 8 is a timing diagram for describing an exemplary operation of adetermination circuit of FIG. 4. For better understanding, FIG. 6 willbe referenced together with FIG. 8.

Exemplary relationships between the first set of conditions c0, thesecond set of conditions c1, and the second set of adjusted conditionsc2 illustrated in FIG. 6 will be described with reference to FIG. 8.Operations of the encoding mode determination circuit 120 to bedescribed with reference to FIG. 8 may correspond to the operations ofthe encoding mode determination circuit 120 described with reference toFIG. 6. Thus, additional description will be omitted to avoidredundancy.

At the time point t4, the determination circuit 123 may determine theencoding mode of the first image data based on information about theconversion value cv0 and the first set of conditions c0. The first setof conditions c0 may correspond to the case where the conversion valuecv0 is between respective lower boundary values b01, b02, b03, b05, andb06 of the first set of conditions c0 and respective upper boundaryvalues b02, b03, b04, b06, and b07 of the first set of conditions c0.For example, the condition c02 in the first set may correspond to thecase where the conversion value cv0 is between the lower boundary valueb02 and the corresponding upper boundary value b03. In the case wherethe conversion value cv0 is between the lower boundary value b02 and thecorresponding upper boundary value b03, the determination circuit 123may determine the encoding mode of the first image data as the encodingmode m2. The boundary values described in this example may correspond,for example, to conversion values having numerical values, for example,between 0 and 70 (or between another minimum and maximum value). Otherboundary values, and other types of conditions, can be used for thefirst set of conditions.

The adjusting circuit 122 may include information about the first set ofconditions c0. For example, the information included in the adjustingcircuit 122 may be the boundary values b01, b02, b03, b04, b05, b06, andb07 of the first set of conditions c0.

At the time point t8, the adjusting circuit 122 may determine the secondset of conditions c1 based on an error value e0, the encoding mode m2 ofthe first image data, and the first set of conditions c0. The errorvalue e0 may correspond to the encoding mode m2 of the first image data.Error values may correspond to the encoding modes m0, respectively. Theerror values may be identical to or different from each other.

The condition c12 in the second set corresponding to the encoding modem2 of the second image data may be generated based on the error value e0and the condition c02 in the first set corresponding to the encodingmode m2 of the first image data. For example, a lower boundary value ofthe condition c12 in the second set may be a value which is obtained bysubtracting the error value e0 from the lower boundary value b02 of thecondition c02 in the first set. An upper boundary value of the conditionc12 in the second set may be a value which is obtained by adding theerror value e0 and the upper boundary value b03 of the condition c02 inthe first set. Accordingly, the range of values in condition c12 in thesecond condition may include all of the values in the range of values ofthe condition c02 in the first set. The error values described above mayrelate to an expected error due to dither or noise, and may be selectedbased on a design requirement or preference. The error values may beupdated based on a change of noise occurring in the display drivercircuit, or a change of dither, so that new ranges are created.

A range of the condition c02 in the first set may be from the lowerboundary value b02 to the corresponding upper boundary value b03. Arange of the condition c12 in the second set may be from the lowerboundary value (b02−e0) to the upper boundary value (b03+e0).Accordingly, the range of the condition c12 in the second condition maybe wider than the range of the condition c02 in the first set.

The remaining conditions c11, c13, c14, and c15 in the second set may begenerated and determined based on a relationship between the conditionsc02 and c12 and the conditions c01, c03, c04, and c05 in the first set.For example, a difference between lower boundary values of theconditions c02 and c12 may be the error value e0.

For example, lower boundary values of the conditions c13, c14, and c15in the second set may be values which are obtained by adding the errorvalue e0 and the respective lower boundary values b03, b05, and b06 ofthe conditions c03, c04, and c05 in the first set. Upper boundary valuesof the conditions c13 and c14 in the second set may be values which areobtained by adding the error value e0 and the upper boundary values b04and b06 of the conditions c03 and c04 in the first set. An upperboundary value of the condition c11 in the second set may be a valuewhich is obtained by subtracting the error value e0 from the upperboundary value b02 of the condition c01 in the first set. The differentranges may be selected based on design requirements or preferences, andas a result, the different sets of conditions may be automaticallygenerated or selected based on a predetermined formula that depends onthe previously selected condition and range as a variable.

The whole range b07 to b01 of the first set of conditions c0 may beidentical to the whole range b07 to b01 of the second set of conditionsc1. For example, the smallest boundary value b01 of boundary values ofthe first set of conditions c0 may be identical to the smallest boundaryvalue b01 of boundary values of the second set of conditions c1. Thegreatest boundary value b07 of the boundary values of the first set ofconditions c0 may be identical to the greatest boundary value b07 of theboundary values of the second set of conditions c1.

The inventive concept is not limited to the above examples, and thesecond set of conditions c1 may be generated in various methods based onthe error value e0 and the first set of conditions c0. For example, adifference between lower boundary values of the conditions c01 and c11may be proportional to the error value e0.

The adjusting circuit 122 may include information about the second setof conditions c1. For example, the information included in the adjustingcircuit 122 may be boundary values of the second set of conditions c1.Thus, a second set of conditions including a second set of ranges may bestored in the adjusting circuit 122.

At the time point t8, the determination circuit 123 determines theencoding mode of the second image data based on the information aboutthe conversion value cv1 and the second set of conditions c1. Forexample, in the case where the conversion value cv1 is between the lowerboundary value b01 of the condition c11 in the second set and the upperboundary value (b02−e0) of the condition c11 in the second set, thedetermination circuit 123 determines the encoding mode of the secondimage data as the encoding mode m1.

At the time point t12, the adjusting circuit 122 selects and uses athird set of conditions c2, which may be based on an error value e1, theencoding mode m1 of the second image data, and the first set ofconditions c0. The error value e1 of the error values may correspond tothe encoding mode m1 of the second image data. The error value e0 may beidentical to or different from the error value e1.

Boundary values of the third set of conditions c2 adjusted anddetermined based on the error value e1, the encoding mode m1 of thesecond image data, and the first set of conditions c0 may correspond toboundary values of the second set of conditions c1 generated based onthe error value e0, the encoding mode m2 of the first image data, andthe first set of conditions c0. Thus, additional description will beomitted to avoid redundancy.

FIG. 9 is a conceptual diagram for describing a difference between afirst set of conditions and a second set of conditions of FIG. 8. Forbetter understanding, FIG. 8 will be referenced together with FIG. 9.

Referring to FIG. 9, the conversion value cv0 obtained from the firstimage data may satisfy the conditions c02 in the first set correspondingto the encoding mode m2. Accordingly, the encoding mode of the firstimage data may be determined as the encoding mode m2.

As described with reference to FIG. 5, the interface 110 may receive thefirst image data and the second image data sequentially and successivelyfrom the main processor 1700. A plurality of image data which are sentsequentially and successively from the main processor 1700 may includethe same or similar information. The first image data and the secondimage data sent sequentially and successively from the main processor1700 may include the same or similar pixel values. Accordingly, in thecase where noise or dither does not occur in the image processingprocess, a conversion value cv11 which is obtained from the second imagedata received immediately after the first image data are received maysatisfy the condition c02 in the first set.

However, in the case where noise or dither occurs in the imageprocessing process, pixel values included in the second image data maybe changed. In this case, the conversion value cv1 may be generatedinstead of the conversion value cv11.

Referring to FIG. 9, the conversion value cv1 obtained from the secondimage data may not satisfy the conditions c02 in the first setcorresponding to the encoding mode m2. Accordingly, in the case wherethe encoding mode determination circuit 120 fixedly determines theencoding mode of the second image data based on the first set ofconditions c0, the encoding mode of the second image data may bedetermined as the encoding mode m1. Accordingly, in the case where theencoding mode is determined based on fixed conditions, the encoding modemay be determined differently with regard to image data including thesame or similar information. In this case, the flicker may occur.

The encoding mode determination circuit 120 according to an embodimentof the inventive concept may determine an encoding mode of each of aplurality of image data based on variable conditions. For example, theencoding mode determination circuit 120 may determine the encoding modeof the first image data and the encoding mode of the second image databased on the first set of conditions c0 and the second set of conditionsc1, respectively. The encoding mode of the second image data may bedetermined as the encoding mode m2, based on the second set ofconditions c1.

Referring to FIG. 9, a range of the condition c12 in the second setcorresponding to the encoding mode m2 of the second image data may bedifferent from (e.g., wider than) a range of the condition c02 in thefirst set corresponding to the encoding mode m2 of the first image data.For example, an upper boundary value (b03+e0) of the condition c12 inthe second set may be higher than the upper boundary value b03 of thecondition c02 in the first set as much as the error value e0. In oneembodiment, the error value e0 may correspond to the greatest differencevalue between the conversion value cv11 and the conversion value cv1,which may occur due to noise or dither. This difference could bedetermined, for example, in advance based on testing, and the amountthat the upper boundary value (b03+e0) of the condition c12 in thesecond set varies from the upper boundary value (b03) of the conditionc02 in the first set may be chosen based on design requirements orpreferences. Accordingly, the inventive concept may prevent each ofencoding modes of a plurality of image data including the same orsimilar information among a plurality of image data receivedsequentially and successively, from being determined differently due tothe noise or dither. As a result, the flicker may decrease.

FIG. 10 is a table indicating an example embodiment of a first set ofconditions and a second set of conditions of FIG. 8. For betterunderstanding, FIG. 8 will be referenced together with FIG. 10.

Boundary values of the first set of conditions illustrated in FIG. 10may be expressed by an integer. Boundary values of the second set ofconditions illustrated in FIG. 10 may be expressed by an integer. Forexample, a lower boundary value b02 and an upper boundary value b03 ofthe condition c02 in the first set corresponding to the encoding mode m1may be “10” and “20”, respectively.

The error value e0 may be “5”. Accordingly, a lower boundary value(b02−e0) and an upper boundary value (b03+e0) of the condition c12 inthe second set corresponding to the encoding mode m2 of the second imagemay be “5” and “25”, respectively. Accordingly, a range of the conditionc12 in the second condition may be wider than a range of the conditionc02 in the first set. The range included in condition c12 in the secondset may include the range included in condition c02 in the first set.

FIG. 11 is a table indicating an embodiment of a conversion valueobtained from image data. For better understanding, FIG. 10 will bereferenced together with FIG. 11.

The generating circuit 121 may receive image data. The generatingcircuit 121 may generate a conversion value based on the received imagedata. The conversion value may be generated based on difference valuesbetween pixel values included in the image data. The image data mayinclude a red (R) pixel value, a green (G) pixel value, and a blue (B)pixel value. The conversion value may be the maximum value among thedifference values between the pixel values included in the image data.

For example, the R pixel value, the G pixel value, and the B pixel valueincluded in the image data may be “90”, “100”, and “102”, respectively.The conversion value cv0 obtained from the first image data may be “12”.Since the conversion value cv0 is between “10” and “20”, by the firstset of conditions c0 illustrated in FIG. 10, the encoding mode of thefirst image data may be determined as the encoding mode m2.

In the case where noise or dither does not occur, information includedin the second image data may be substantially identical to informationincluded in the first image data. The R pixel value, the G pixel value,and the B pixel value included in the third image data may be “90”,“100”, and “101”, respectively. The conversion value cv11 obtained fromthe second image data may be “11”. Since the conversion value cv11 isbetween “10” and “20”, by the first set of conditions c0 illustrated inFIG. 10, the encoding mode of the second image data may be determined asthe encoding mode m2.

However, due to noise or dither, pixel values included in the secondimage data may be changed. The R pixel value, the G pixel value, and theB pixel value included in the second image data may be changed to “90”,“100”, and “98”, respectively. The conversion value cv1 obtained fromthe second image data may be “8”. Since the conversion value cv1 is notbetween “10” and “20”, in the case where the encoding mode determinationcircuit 120 fixedly determines the encoding mode of the second imagedata based on the first set of conditions c0, the encoding mode of thesecond image data may be determined as the encoding mode m1 since theconversion value cv1 (“8”) is between “0” and “10”, by the first set ofconditions c0 illustrated in FIG. 10.

The encoding mode determination circuit 120 according to an embodimentof the inventive concept may determine the encoding mode of the secondimage data variably based on the second set of conditions c1. Since theconversion value cv1 (“8”) is between “5” and “25”, by the second set ofconditions c1 illustrated in FIG. 10, the encoding mode of the secondimage data may be determined as the encoding mode m2.

FIG. 12 is a flowchart for describing an operation of a display drivercircuit from a time when first image data of FIG. 5 are received to atime when an encoding mode of second data is determined. For betterunderstanding, FIG. 5 will be referenced together with FIG. 12.

In operation S110, the interface 110 receives the first image data fromthe main processor 1700.

In operation S120, the encoding mode determination circuit 120 receivesthe first image data from the interface 110. The encoding modedetermination circuit 120 determines the encoding mode of the firstimage data based on the first set of conditions.

In operation S130, the encoder 130 encodes the first image data in thedetermined encoding mode.

In operation S140, the memory 140 stores the encoded first image data.

In operation S150, the decoder 150 decodes the first image data storedin the memory 140.

In operation S160, the interface 110 receives the second image data fromthe main processor 1700.

In operation S170, the encoding mode determination circuit 120 receivesthe decoded first image data. The encoding mode determination circuit120 may identify the encoding mode of the first image data based on thedecoded first image data. The encoding mode determination circuit 120may then select or generate the second set of conditions based on theencoding mode of the first image data and the first set of conditions.

In operation S180, the encoding mode determination circuit 120 receivesthe second image data from the interface 110. The encoding modedetermination circuit 120 determines the encoding mode of the secondimage data based on the second set of conditions.

FIG. 13 is a flowchart for describing an operation of an encoding modedetermination circuit until an encoding mode of second image data isdetermined after first image data of FIG. 5 are received. For betterunderstanding, FIGS. 5 and 6 will be referenced together with FIG. 13.

In operation S210, the generating circuit 121 receives the first imagedata from the interface 110.

In operation S220, the generating circuit 121 generates the conversionvalue cv0 from the first image data.

In operation S225, operation S230, and operation S235, the determinationcircuit 123 determines the encoding mode of the first image data basedon the conversion value cv0 and the first set of conditions c0. Thedetermination circuit 123 may determine a condition that the conversionvalue cv0 satisfies, from among the first set of conditions c0. Thedetermination circuit 123 may first check whether the conversion valuecv0 satisfies the condition c01 in the first set corresponding to theencoding mode m1. In the case where the conversion value cv0 does notsatisfy the condition c01 in the first set, the determination circuit123 may check whether the conversion value cv0 satisfies the conditionc02 in the first set corresponding to the next encoding mode m2, andthis process may repeat until a condition which the conversion value cv0satisfies is found. However, the inventive concept is not limitedthereto, and the order in which the conditions c0 in the first set arechecked may be set arbitrarily.

In operation S240, the determination circuit 123 generates the signal s1including information about the determined encoding mode of the firstimage data. The determination circuit 123 sends the signal s1 to theencoder 130.

In operation S250, the generating circuit 121 receives the second imagedata from the interface 110.

In operation S260, the generating circuit 121 generates a conversionvalue from the second image data.

In operation S270, the adjusting circuit 122 receives the decoded firstimage data. The adjusting circuit 122 may identify an encoding mode ofthe first image data based on the decoded first image data.

In operation S280, the adjusting circuit 122 generates (e.g., selects)the second set of conditions c1 based on the encoding mode of the secondimage data and the first set of conditions c0. In this manner, anadjusted set of conditions may be used as the second set of conditionsc1.

In operation S285, operation S290, and operation S295, the determinationcircuit 123 may determine an encoding mode of the second image databased on the conversion value cv1 and the second set of conditions c1.The determination circuit 123 may determine a condition, which theconversion value cv1 satisfies, from among the second set of conditionsc1. The determination circuit 123 may first check whether the conversionvalue cv1 satisfies the condition c11 in the second set corresponding tothe encoding mode m1. In the case where the conversion value cv1 doesnot satisfy the condition c11 in the second set, the determinationcircuit 123 may check whether the conversion value cv1 satisfies thecondition c12 in the second set corresponding to the next encoding modem2, etc. However, the inventive concept is not limited thereto, and theorder in which the conditions c1 in the second set are checked may beset arbitrarily.

In operation S297, the determination circuit 123 generates the signal s1including information about the determined encoding mode of the secondimage data. The determination circuit 123 may send the signal s1 to theencoder 130.

FIG. 14 is a flowchart for describing an operation of an adjustingcircuit until an encoding mode of third data is determined after secondimage data of FIG. 5 are received. For better understanding, FIG. 5 willbe referenced together with FIG. 14.

In operation S310, the adjusting circuit 122 outputs the signal s3 tothe determination circuit 123. The signal s3 may include informationabout the first set of conditions c0 (e.g., it may include the first setof conditions c0). The determination circuit 123 may determine anencoding mode of the first image data based on the first set ofconditions c0.

In operation S320, the adjusting circuit 122 receives the decoded firstimage data. The adjusting circuit 122 may identify an encoding mode ofthe first image data based on the decoded first image data.

In operation S330, the adjusting circuit 122 generates or selects thesecond set of conditions c1 based on the encoding mode of the secondimage data and the first set of conditions. Thus, an adjusted set ofconditions may be used as the second set of conditions c1.

In operation S340, the adjusting circuit 122 sends the signal s3 to thedetermination circuit 123. The signal s3 may include information aboutthe second set of conditions c1 (e.g., it may include the second set ofconditions c1). The determination circuit 123 may determine an encodingmode of the third image data based on the second set of conditions c1.

In operation S350, the adjusting circuit 122 receives the decoded secondimage data. The adjusting circuit 122 may identify the encoding mode ofthe second image data based on the decoded second image data.

In operation S360, the adjusting circuit 122 checks whether the encodingmode of the first image data and the encoding mode of the second imagedata are identical to each other.

In the case where the encoding mode of the second image data and theencoding mode of the first image data are identical to each other, inoperation S370, the adjusting circuit 122 maintains the second set ofconditions c1.

In the case where the encoding mode of the second image data and theencoding mode of the first image data are different, in operation S375,the adjusting circuit 122 changes the second set of conditions c1 to thethird set of conditions c2.

In operation S380, the adjusting circuit 122 sends the signal s3 to thedetermination circuit 123. The signal s3 includes information about thesecond set of conditions c1 (e.g., it may include the second set ofconditions c1). The determination circuit 123 determines an encodingmode of the third image data based on the second set of conditions c1.

In operation S385, the adjusting circuit 122 sends the signal s3 to thedetermination circuit 123. The signal s3 includes information about thethird set of conditions c2 (e.g., it may include the third set ofconditions c2). The determination circuit 123 determines the encodingmode of the third image data based on the third set of conditions c2.

In some embodiments, the encoding mode determination circuit 120 may beimplemented with a hardware circuit (e.g., an analog circuit or adigital/logic circuit) configured to perform the above-describedoperations. In the embodiments, the hardware circuit of the encodingmode determination circuit 120 may be designed to output intended outputvalues or signals based on given input values or signals.

In some embodiments, the above-described operations of the encoding modedetermination circuit 120 may be implemented with a program code ofsoftware/firmware, and the encoding mode determination circuit 120 mayinclude a processor core which may execute an instruction set of theprogram code. In the embodiments, the program code may be written toinclude information about various numerical values and to provide outputvalues corresponding to given input values.

In some embodiments, the encoding mode determination circuit 120 may beimplemented in a hybrid form of hardware and software. In theembodiments, some of operations of the encoding mode determinationcircuit 120 may be implemented on a hardware circuit, and the remainingoperations may be implemented on a processor core. For example, thehardware circuit and the processor core may include a dedicated circuitsuch as a field programmable gate array (FPGA) or application specificintegrated circuits (ASICs).

In some embodiments, information associated with encoding modes andconditions may be stored in a memory element (e.g., a register or alookup table). The memory element may be included within the encodingmode determination circuit 120 or may be provided on the outside of theencoding mode determination circuit 120. In some embodiments, theinformation associated with the encoding modes and the conditions may beinserted into the program code, and data of the program code may bestored in the memory element.

According to an embodiment of the inventive concept, a display drivercircuit may determine an encoding mode for encoding image data inconsideration of an error occurring in the image data. According to anembodiment of the inventive concept, the display driver circuit mayprevent an encoding mode of each of a plurality of image data receivedsequentially and successively from being determined differently due tonoise or dither. As a result, a flicker due to the noise or dither maydecrease.

While the inventive concept has been described with reference toexemplary embodiments thereof, it will be apparent to those of ordinaryskill in the art that various changes and modifications may be madethereto without departing from the spirit and scope of the invention asset forth in the following claims.

What is claimed is:
 1. A display driver circuit comprising: an encodingmode determination circuit configured to select a first encoding modefor encoding first image data based on a first set of conditionsrespectively corresponding to a first set of encoding modes; and anencoder configured to encode the first image data in the first encodingmode, wherein the encoding mode determination circuit is furtherconfigured to: select a second encoding mode for encoding second imagedata received (n−1)th after the first image data are received; andselect a third encoding mode for encoding third image data received(n)th after the first image data are received, based on a second set ofconditions respectively corresponding to the first set of encodingmodes, wherein n is integer greater than one, and wherein a secondcondition in the second set of the conditions corresponding to thesecond encoding includes wider range of values than a first condition inthe first set of the conditions corresponding to the second encodingmode.
 2. The display driver circuit of claim 1, configured such that thefirst set of the conditions being used for selecting the first encodingmode are updated periodically or randomly.
 3. The display driver circuitof claim 1, wherein the first image data is image data first receivedafter the display driver circuit is reset.
 4. The display driver circuitof claim 1, wherein the encoding mode determination circuit is furtherconfigured to: select the third encoding mode based on the first set ofthe conditions in a case where the third image data are first receivedafter the display driver circuit is reset.
 5. The display driver circuitof claim 1, wherein the encoding mode determination circuit is furtherconfigured to: generate the conditions in the second set of theconditions based on the second encoding mode and the conditions in thefirst set of the conditions.
 6. The display driver circuit of claim 1,wherein the encoding mode determination circuit is further configuredto: determine the third encoding mode as the same encoding mode as thesecond encoding mode in a case where a conversion value obtained fromthe third image data satisfies the second condition.
 7. The displaydriver circuit of claim 6, wherein the encoding mode determinationcircuit is further configured to: maintain the conditions in the secondset of conditions and use those as a fourth set of conditions which isused for selecting a forth encoding mode for encoding forth image datareceived immediately following the third image data in a case where theconversion value satisfies the second condition.
 8. The display drivercircuit of claim 6, wherein the encoding mode determination circuit isfurther configured to: generate the conversion value based on pixelvalues included in the third image data.
 9. The display driver circuitof claim 1, wherein the third image data are associated with an image tobe displayed on a display panel, and wherein a color to be expressed inthe image varies with the third encoding mode.
 10. The display drivercircuit of claim 9, wherein, in a case where the third encoding mode isa first mode of the encoding modes, the color of the image is expressedin a combination of first colors corresponding to the first mode, andwherein, in a case where the third encoding mode is a second mode, whichis different from the first mode, from among the encoding modes, thecolor of the image is expressed in a combination of second colorscorresponding to the second mode.
 11. A display driver circuitcomprising: an encoding mode determination circuit configured to receivefirst image data, second image data, and third image data sequentiallyand successively, select a first encoding mode for encoding the firstimage data among a plurality of encoding modes, select a second encodingmode for encoding the second image data among the encoding modes basedon a first set of conditions respectively corresponding to the encodingmodes, the first set of conditions including a first conditioncorresponding to the second encoding mode, and select a third encodingmode for encoding the third image data among the encoding modes based ona second set of conditions respectively corresponding to the encodingmodes, the second set of conditions including a second conditioncorresponding to the third encoding mode; and an encoder configured toencode the first image data in the first encoding mode that selected,and to encode the second image data in the second encoding mode thatselected, wherein, in a case where the second encoding mode is differentfrom the first encoding mode, a second range corresponding to the secondcondition is wider range than a first range corresponding to the firstcondition.
 12. The display driver circuit of claim 11, wherein thesecond set of conditions are an adjusted set of conditions based on thefirst set of conditions.
 13. The display driver circuit of claim 11,wherein, in a case where the first encoding mode is identical to thesecond encoding mode, the first range is identical to the second range.14. The display driver circuit of claim 11, wherein the encoding modedetermination circuit is further configured to: select the secondencoding mode based on the conditions in the first set and a conversionvalue, the conversion value being obtained from the second image data.15. The display driver circuit of claim 11, wherein a difference betweenthe first range corresponding to the first condition and the secondrange corresponding to the second condition is associated with an errorvalue corresponding to the first encoding mode.
 16. The display drivercircuit of claim 15, wherein the error value is associated with noiseoccurring in the display driver circuit, or dither.
 17. The displaydriver circuit of claim 11, wherein the encoding mode determinationcircuit is further configured to in a case where the third encoding modeis determined based on conditions of a predetermined reference set and a(n−1)th encoding mode for encoding (n−1)th received image data after thefirst image data is received is different from the third encoding mode,select a (n)th encoding mode for encoding (n)th received image dataafter the first image data are received based on a (n)th set ofconditions, the predetermined reference set of conditions and the (n)thset of conditions including a (n−1)th condition and a (n)th conditioncorresponding to the (n−1)th encoding mode, respectively, and wherein a(n)th range corresponding to the (n)th condition is wider range than a(n−1)th range corresponding to the (n−1)th condition.
 18. A displaydriver circuit comprising: an encoding mode determination circuitconfigured to determine a first encoding mode for encoding first imagedata based on a first set of conditions corresponding to encoding modes,the first set of conditions including a first condition, and determine asecond encoding mode for encoding second image data received immediatelyfollowing the first image data, based on a second set of conditionscorresponding to the encoding modes, the second set of conditionsincluding a second condition; and an encoder configured to encode thefirst image data in the first encoding mode, wherein the first conditionin the first set of conditions includes a first range or set ofcriteria, and the second condition in the second set of conditionsincludes a second range or second set of criteria, wherein the secondrange is wider than and includes the first range, or the second set ofcriteria includes the first set of criteria.
 19. The display drivercircuit of claim 18, further comprising: a memory configured to storethe encoded first image data; and a decoder configured to decode thestored first image data, wherein the encoding mode determination circuitis further configured to: identify the first encoding mode based oninformation included in a header of the stored first image data or thedecoded first image data.
 20. The display driver circuit of claim 18,wherein the encoding mode determination circuit is further configuredto: determine the second encoding mode as an encoding mode differentfrom the first encoding mode in a case where a conversion value obtainedfrom the second image data satisfies a third condition, which isdifferent from the first condition and does not include the first rangeor set of criteria, from among the conditions in the second set ofconditions.